Primary frequency regulation capacity is one of main representations of capabilities of a power system to realize a balance between power generation and loads and to respond to an accident or a disturbance. Traditional primary frequency regulation is generally provided by hydropower generating units or large-scale thermal power generating units having a quickly regulating capability with a response time of seconds. With the connection of large-scale new energy power generation, moment of inertia of the power system is significantly reduced, and randomness and uncontrollability of the power generated in new energy generation may increase frequency regulation burden of the power system. Meanwhile, connection of high voltage direct current transmission replaces a local power source, which further reduces the primary frequency regulation capacity of the system. Therefore, how to develop potentials of the load side to involve in the primary frequency regulation of the system becomes a pressing issue.
Based on load side response mechanism, a viable idea is to organize and manage numerous controllable thermal loads with low monomer power to participate in the primary frequency regulation of power system. Via collecting and processing information and certain control means, cluster loads with thermal energy storage effect, such as air conditioners, may be able to participate in ancillary services, while ensuring comfort of an end user is not significantly affected. This is because that the controllable thermal loads are energy type loads, users care about the total thermal energy released by a power consumption equipment to a thermal environment during a period of time rather than the power at each moment. While an error signal of the primary frequency regulation is an impulse type signal with integration within a period of time approaching to zero, thus will not cause significant change in the final energy output. Meanwhile, the controllable thermal loads have occupied more and more proportions of the total loads and have great potentials. In America, the controllable thermal loads in buildings account for more than 35% of the total power consumption loads of the whole power grid. Air conditioner loads also grow fast in China, where the air conditioner loads may account for more than 20% of the maximum loads of the power grid in summer. Therefore an air conditioner cluster may have a great potential of being a reserve frequency regulation means.
In addition, autonomous temperature dead zone control set for ensuring comfort of users of an air conditioner may cause total power of the air conditioner cluster to change against a requirement of a power-frequency response at some time point, that is a so-called rebound effect. The rebound effect may greatly limit thermal energy storage loads to participate in a load side response and to provide ancillary services to the system.